Chronic Benign Congenital Myopathy: Fingerprint Body Type

Abstract

SUMMARY The term “benign congenital myopathy” describes a group of muscle disorders characterized by proximal or diffuse muscle weakness, a relatively non-progressive course, normal serum muscle enzyme assays and the presence of a distinctive morphological feature. We report here a 55 year old woman, with fingerprint body myopathy who exhibits all of the above features. She has been affected from birth, able to walk since the age of 12, and has not deteriorated in the past thirty years. Muscle biopsy reveals fatty infiltration, numerous small fibers undergoing structural change, good differentiation into type I and II fibers, and excessive intracellular lipid and lipochrome. Only on electron microscopic study is the distinctive feature of numerous subsarcolemmal round to ovoid fingerprint bodies observed. Many fibers also contain large collections of tubular aggregates, filamentous bodies, and autophagic vacuoles. The fingerprint bodies are similar to the ones described by A. Engel in a 5 year old girl. Thus, a rare opportunity is provided to study an individual who has had this disease for over fifty years.